Micrometer



Sept. 14; 1943. w EDDY 2,329,598

' MICROME'IER Filed Sept. 11, 1941 I INVENTOR (%aB'Y/a/6' dbf'y TTORNEYS'.

Patented Sept. 14, 1943 2 11 5. 11 i V I R METEK; j Charles W; Eddy, EastProvillfe'nceg lt iil ii1 Application-September11, 1941, Serial No; 410,419

' -e1m (Creamery This invention rel ates. to. sm all .m'easuifingt tools such; for: instance, mas-a micrometer;

It is usual "in the 'manufacturesof Emicrometers to lap the threaded measuring-zrodiintoithreads ins t'he barrel in order: thatspferfecti fita-of these two parts, which" 'require'xgreaztz accuracy in. meas= .u-rement, mam-be had; such lapping :causes; each instrument .to,,be-individual that :themeasur 'ing rod-s: arenot: interchangeable and. cannotbe 1 1 1 47861 from stocky: asi'a :new': measuring rod thus mustbe"lapped.-intor 'thez'barrehii..thesparts require-replacement; This manneri of: assembly is costly. In the manufacture OfTIXfiCI'OIIlEtGIS of the type herein illustrated, some adjustment .of gthe anvil h'as:heretofore; beenaplovided so that if .the. measuringigraduations doarnotzline up. cor; rectly. thez grad-nations? may be: setzat zero: and an adjustmentvof' the "anvil: made: "so that t'he readings will-.measurecorrectly-fromca: zeropoint Such. an adjustment of :the a'nvil makes: necessary additional-- parts; that such adjustment mayibe had. It is also usual-immicrometersto havesome resilient action 1 between; the measuring: rod: and

the barrel-:for Wear:compeusatiorn The-amount" of. resilient action-is.-,usua11y, a'd-justed by some separate part, also requiring careful and skillful assembly operations.- 1 This invention has for s0116101?pitS:-"ObjCtSfi to provide. a. fewer. number of rparts -than -is"usua'l in micrometers.of-thischaraeter and anarrange- I ment {of the: parts used. so that-lassemblyioperaq tionsandJconsequent: assembl-y'costs-may be'isirn plifieduandmreduceda. a Another object of the invention-is to: make-the parts of themicrometer: so that thei parts'may 1 be interchanged .andeassembled :wi-thcuts the ne'-. cessity, oilapping, in-.the-. pa.rt's and thus: make an instrument iwhichds. not individual-An? char:- acterbut ratherione which 1573 product .of multiple unit production with asimple assembly-open ation.

Another object ofwtheinventioneis toprovide aninstrument in which adjustment ofith'e zmeas uring rodfor registerir-ig'. '0f..the-- calibrated: scale may. occur. without shifting-wot -;thean viil.

Another objector the invention-is to provide for -theadjustment ofthe measuringvrod to's'cause registry of the ca-libratedrgscale in apredeter mined. calculated amount without; necessity of depending upon trial and error.

Anotheriobject .ot the-invention is :to minimize localwearalong the threads: of :tlrermeasuring r0d.. I

Another object. of thednventionis: to provide for ithe-rslippingwbyyoithreads-betweenthe parts if'tooxgrea't :a pressure iszbrought to bear .on the measuring :rod bymea'sonzof: turning'thereof into too. tight. atpositiome particularlymgointed"outiin the. appended claims;

:Inmth'e accompanying:.drawing: I I.

Fig. 1 is a plan view of the micrometer made in r accordance with'sithisl'; invention Fig: 2 is a section-through ."theiibarrel, thimble andxnutrmember 'provi'dedzin mysinstrument; J

Fie y-3 isa sectior'r airline 3+3rof Fig. 2'; Fig-:24 is an elevation,"partlybroken' away, illus= trating thevnut member aboutwhich thisinven Fign5 is: an en'di-aview 'ofzone end of this nut member; ,7 e .;Fig:.-,,6 isra'n' end yiew of'theh other endiof the nutmemberyandx -Fig.-.:'7=i;s.=-.a perspective view; of a portion'rof the barrel; ai-portion-rof' the' nutJmen'Iber, and a por-' tion of the threaded part of. the measuring rod, showing:- certain relationships between these partsw With reference- 130: the drawing, 1 il'designates 'asatfwz'andfprdvided with radua-tions to'be read u ithtthemeasuring g ra'duations on the barrel. The thi eads' lfi of the 'measuring red are usually forty tl'ireads-tdthe' inch, while th'e divisions on the bevel 'porti'on 2 0 areusually twenty-five in number so tha-t measurementsin one one-thousandth of an inch" maybe indicated.

Thefpartswhich areso far described are partswhich are. familianparts-bf a "micrometer caliper of-ithe type totwhichthis inventicn relates. How= ever, in connectiomwiththis inventionythe barrel 1 3; is modified 'an-df I havezpro-vided' anew part, designated 1 generaliyii 2i and: shown by;- itself; in Fig,4,' WhiCH is Za-nut ir'ne'mber. supported by the;

barrel and is the part about which this invention centers.

beyond the threaded portions in which they are 7 located and extend one past the other in the non-threaded portion of the sleeve in the mid portion between the two threaded portions These slots provide for considerable resilience of the sleeve. a

The long slots 25 and 26 provide for a long resilient leverage arm in which the threads of the nut are located and thus an arrangement where a large number of threads willibe' caused to engage the threads of the rod even though flexing occurs and a corresponding greater distribution of wear by reason of this engagement will occur. Thus, the usual wear point is not as localized in this instrument as in the instruments vdth which I have heretofore been familiar.

The long slots are sufficiently wide as to leave corresponding arms which carry the threads of such an arc as to provide for sufficient movement of the arms to permit the arms springing apart and out of engagement with the threads N of the measuring rod, should too' great a pressure be brought to bear by screwing the rod against the anvil or against some work which is being measured intermediate the ends of'the rod and the anvil and thus would prevent damage occurring to the instrument, such as 'to the frame, the threads going back into place nicely upon release of this pressure. This may take the place of the ratchet stop.

The nut 2| has its threads 23 engaging internal threads 21 in the barrel spaced inwardly from one end thereof, while the threads '24 engage the threads IS on the measuring rod. The arrangement of the resilience caused bythe slots no to the position in which the nut is held while handling relative to the part which is to'be engaged is such that the greater tension will be exerted upon the part which the threads 23 engage than the exertion of pressure on the parts which the threads 24 engage. By the arrangement of the different forces exerted by these resilient portions of the nut, should the measuring rod be turned with reference to the barrel, this measuring rod will be advanced or retracted along the threads 24 rather than the nut being turned because of the greater holding pressure between the nut and the barrel than between the measuring rod and the nut. However, if desired, some other means may be provided for relatively holding the nut member 2| and the barrel in none-rotative position after the adjustment has been made. I In order to provide for adjustmentthat the graduations may properly register, I provide a different pitch of the threads 23 than of the threads 24; for instance, there may be provided approximately thirty-nine threads per inch of the threads 23, whereas I provide, as stated before, forty threads per inch of the threads 24. By reason of this differential, I may adjust the nut 2| in the barrel so that thegraduations maybecome properly registered and make adjustment of the anvil unnecessary. In order to assist in this adjustment, I have provided graduations 28 running longitudinally along the outer surface of the nut member 2| and have provided an indicia mark 29 on the end 30 of the barrel. For instance, I may provide six of such marks 28 evenly spaced about the barrel which, upon the selection of the proper number of threads per inch at 23 relative to forty threads per inch at 24, will provide one-ten-thousandths of adjustment for the relative rotation of the nut member 2| with reference to the barrel I3. Such selection is a fraction from thirty-nine threads per inch. Thus, should I find that there is an error of three-ten-thousandths between the end of the measuring rod and the end of the anvil, I may adjust the nut 2| 2. distance corresponding to three of the graduations 28 to overcome this discrepancy; and by this arrangement I provide the mathematical means of calculation 'of error in the instrument which may be at once quickly compensated for by adjustment without necessity of trial and error.

By reason of the construction which I have provided and the'adjustment with the long'easy resilience of the nut, the parts areinterchangeable between the different instruments, and it is unnecessary to lap the threads of the measuring rod into the threads which cause the movement of the measuring rod and thus make each instrument specialized to the extent that interchange cannot be had.

I I claim:'

1. In a micrometer having a frame, an internally threaded barrel, and athreaded measuringrod, aseparate memben 'thrads for adjustably'securing the member to said barrel, said member being provided'with threadsengaging the threads of said measuring rod for advancement of said rod uponrotation relative to said member, said member being longitudinally split from opposite ends thereof to provide resilience of the member and saidmember resiliently engaging the threads of said measuring rod and said barrel.

2. In a micrometer having a frame, a barrel, and a threaded measuring rod, a separate member, means for adjustably securing the member to said barrel, said member being provided with threads engaging the threads of said measuring rod for advancement of said rod upon rotation relative to said member, said member being longitudinally split from opposite ends thereof to provide resilience'of the'member and said member resiliently engaging said measuring rod and said barrel, and the resilience of the engagement of said member at its opposite end portions being such that greater pressure is exerted on said barrel than on said measuring rod.

3. In a micrometer having a frame, a barrel, and a threaded measuring rod, a separate member threaded into said barrel and provided with threads engaging the threads of said measuring rod for axial movement of said rod upon rotation relative to said member, said member being longitudinally split from opposite ends thereof to provide resilience of the member and said member resiliently engaging said measuring rod and said barrel.

4. In a micrometer having a frame, a barrel, and a threaded'measuring rod, a separate member threaded into said barrel and provided with threads engaging the threads of said measuring rodfor axial movement of said rod upon rotation relative to said member, said member beinglongitudinally split from opposite ends thereof to provide resilience of the member and said member resiliently engaging said measuring rod and said barrel, and the resilience of the engagement of said member at its opposite end portions be-' ing such that greater pressure is exerted on said barrel than on'said measuring rod.

5. In a micrometer having a frame, an in-.

ternal threaded barrel and a threaded measuring rod, a separate member provided with threads engaging the threads of said barrel and threadingly engaging the threads of said measuring rod for advancement of said rod'upon rotation relative to said member, said member being longitudinally split along said threads engaging said 10 measuring rod for advancemento-f said rod upon rotation relative to said member, said member {being longitudinally split throughout and along said threads to provide resilience of the member to frictionallyresiliently engage the threads of 15 the measuring rod and the threads of said barrel. I

CHARLES ,w. EDDY. 

